It is a long-standing objective of color photographic origination materials to maximize the overall response to light while maintaining the lowest possible granularity. Increased photographic sensitivity to light (commonly referred to as photographic speed) allows for improved images captured under low light conditions or improved details in the shadowed regions of the image. In general, the overall light sensitivity provided by the light-sensitive silver halide emulsions in such systems is determined by the size of the emulsion grains. Larger emulsion grains capture more light. Upon development, the captured light is ultimately converted into dye deposits which constitute the reproduced image. However, the granularity exhibited by these dye deposits is directly proportional to the grain size of the silver halide emulsion. Thus, larger silver halide emulsion grains have higher sensitivity to light but also lead to higher granularity in the reproduced image. Therefore, it is a fundamental problem in photography to improve the light sensitivity of a silver halide element without a corresponding increase in another property such as granularity. In this description, it will be understood that the demonstrated increase in sensitivity is accomplished without a significant sacrifice in granularity. Stated from another perspective, it has been a long-standing problem to provide materials which maximize the response to light of a silver halide emulsion for any given grain size.
For example, it is well known that highly reactive couplers or couplers that form dyes with high extinction coefficients can maximize the response of silver halide emulsions. However, the increased amplification caused by these types of dye forming materials also directly leads to higher granularity.
It is highly desirable to provide non-imaging materials that lead to increased photographic speed without having to increase the size of the light-sensitive silver halide grains. Ideally, the addition of such materials should not require the use of permanent solvents (non-reactive, non-volatile organic liquids with low aqueous solubility) in order to be introduced or effective in a photographic film. The use of such permanent solvents is generally unfavorable because of cost, film thickness, increased total organic load and environmental factors.
JP 4-107446 describes the use of substituted purines in combination with separate carbonamide substituted polymers in graphic arts systems. U.S. Pat. No. 3,779,769 describes the use of tetraazindenes in combination with separate sulfated vinyl copolymers.
Copending application U.S. Ser. No. 09/221,359 describes the use of certain polymeric heterocycles derived from a monomeric heterocycle with a ClogP of 6.2 or greater to increase the light sensitivity of a photographic element.
U.S. Pat. Nos. 5,213,959 and 5,275,931 describe the use of heterocyclic antifoggants that have a reactive substituent that chemically reacts with the dispersing medium to form a covalent bond in a photographic element to prevent diffusion.
U.S. Pat. Nos. 3,753,956 and 3,576,638 describe the use of polymeric tetrazoles for use as antifoggants.
JP 62-000949A describes the use of polymeric oxadiazoles, thiadiazoles and selenodiazoles as antifoggants, in which all but two examples are substituted with a free thiol group. The two examples that do not have a free thiol group (polymers 8 and 10 on page 392) are based on monomers with ClogP of less than zero.
U.S. Pat. Nos. 3,598,600 and 5,702,877 describe the use of polymeric benzodiazoles in photographic films.
JP 64-019343A2 describes the use of polymeric thiol substituted 1,2,3a,7 and 1,3,3a,7-tetraazaindenes as antifoggants. JP 06-059363A2 describes the use of polymeric 6-hydroxy-1,3,3a,7-tetraazaindenes as addenda for silver halide precipitations. JP 61-134758 describes the use of polymeric 6-hydroxy-1,3,3a,7-tetraazaindenes and polymeric benzotriazoles as antifoggants in instant photography.
U.S. Pat. Nos. 4,528,264 and 5,229,249 describe the use of polymeric benzotriazoles.
A problem to be solved is to provide color photographic elements that exhibit improved photographic speed and methods for processing such elements. In particular it is desirable to provide improved speed using compounds useful over a broader range of ClogP values than heretofore available.